GIMP Deep Color: patch for 16-bit support of PNG
By mjhammel ~ February 10th, 2009. Filed under: GIMP News.
For those who don’t read the GIMP-Developer mailing list, the long wait for 16-bit channel support may have just started to inch it’s way to a close. Martin Nordholts posted the following back at the end of January:
I have attached a patch to Bug 74224 – Add support for 16 bits per channel that makes it possible to use GIMP for opening, color correcting and saving 16-bits-per-channel PNGs using the operations under the Colors menu that are ported to GEGL such as Color Balance or Levels. For a technical description of the patch, refer to the bug report.
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Welcome to the start of the 16-bit GIMP era 
Martin also questioned whether it was time to consider shooting for at least particla 16-bit support in 2.8. According to his research:
[Martin doesn't] think it will be hard to add support for loading some additional 16-bit image formats, allowing creation of 16-bit images and adding 16-bit capabilities to a set of basic tools.
So the first public step toward 16-bit channels has seen the light of day. Now it’s not clear if this patch has been accepted into the mainline (I don’t think that decision was made on the mailing list, if its been made at all – the bug report has no additional information on that) but at least a public note of work in this area has surfaced, something beyond just working on getting gegl prepared for use by GIMP developers. Now it’s actually in use.
its about time! i noticed that the CinePaint project kind of died. there was not a post to the site since 2008, and it is now 2010. now if they could put support for openexr into gimp that would be awesome.
GEGL supports OpenEXR so I would imagine its just a matter of finding someone to integrate that support into GIMP. I saw a developer mailing list discussion in Jan 2009 that mentioned this but as of today I don’t see an OpenEXR option in the file->open dialog in the 2.7 GIT source.